1. Field of the Invention
This invention relates to window sash locks and in particular to window sash locks having automatic means for effecting a locking operation as an incident of movement of the window members to te closed position.
2. Description of the Prior Art
A number of improved sash lock structures are shown in applicant's prior U.S. Letters Pat. Nos. 2,421,196, 2,480,016 and 2,846,258. In each of these patents, a sash lock is disclosed for use in locking relatively movable members. In each sash lock, a latch plate is pivotally mounted to a base for selective engagement with a catch carried on the other window member.
In U.S. Pat. No. 2,480,016, a locking element is provided for providing an automatic locking of the structure when the window members are brought to the closed position.
In U.S. Pat. No. 2,846,258, an improved lock structure is provided wherein a control member is biased by a spring to provide the desirable control functioning.
In U.S. Letters Pat. No. 2,884,276 of Arthur H. Baptist, which patent is owned by applicant hereof, an automatic window sash lock is disclosed wherein the control means is mounted on a mounting plate secured to the latch base. The control means is provided with a biasing spring to function generally similarly to the functioning of the Granberg U.S. Pat. No. 2,486,258 sash lock.